Search

Your search keyword '"Peterson, James T."' showing total 2 results
Start Over Author "Peterson, James T." Search Limiters Full Text Region alaska
2 results on '"Peterson, James T."'

1. Using a Bayesian Multistate Occupancy Model to Assess Seabird and Shorebird Status in Glacier Bay, Alaska.

Author

Whitlock, Steven L., Lewis, Tania M., and Peterson, James T.

Subjects
*WATER birds, *SHORE birds, *GLACIERS, *PARK use, *NATIONAL parks & reserves, *BAYS
Abstract

The U.S. Department of Interior National Park Service is charged with both monitoring avian communities and evaluating the influence of visitors to National Parks on sensitive species; however, this task is challenging considering that sampling programs often involve multiple species, each with differing behavior, habitat requirements, and detectability. Our objectives were to build a model to describe the status of waterbirds in Glacier Bay National Park, Alaska, USA, and assess effects of area closures on these species. We used a Bayesian multistate occupancy model to describe the status of multiple species and make the best possible use of existing survey data. We modeled up to 5 states per species and evaluated predictors of occupancy, nesting, and abundance, as well as survey‐related predictors of state‐dependent detection probability. We found that occupancy probability varied across species and habitats (islands vs. glacial outwashes). For most species, occupancy probability was substantially greater at sites occupied in the year previous (site persistence). We found weak evidence that area closures affected the occurrence of species in the study, but this was largely because most sites were closed for the entirety of the study period. The probability of detecting occurrence, nesting, and abundance varied across species and survey methods (ground vs. vessel). Detection parameters provided valuable information for enhancing the efficiency of future surveys, by identifying preferred survey methods and sampling periods for specific waterbird species. © 2020 The Wildlife Society. National Parks are charged with monitoring sensitive species and assessing the effects of potential visitor disturbances. We used a Bayesian multistate occupancy model to provide a framework for modeling the occupancy, nesting status, and disturbance of waterbirds at islands and glacial outwashes in Glacier Bay National Park, Alaska, USA. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

2. Modelling pinniped abundance and distribution by combining counts at terrestrial sites and in-water sightings.

Author

Whitlock, Steven L., Womble, Jamie N., and Peterson, James T.

Subjects
*SEA lions, *AQUATIC animals, *AERIAL surveys, *PINNIPEDIA, *COUNTING, *WATER storage
Abstract

• Model for integrating pinniped survey data from aerial counts with sightings-at-sea • Allows for the estimation of abundance, distribution, attendance at sites • Applied to Steller sea lions in Glacier Bay, Alaska • Estimates were biologically reasonable and comparable to previous studies • The modelling framework is generalizable to other species and systems Pinnipeds are commonly monitored using aerial photographic surveys at land- or ice-based sites, where animals come ashore for resting, pupping, molting, and to avoid predators. Although these counts form the basis for monitoring population change over time, they do not provide information regarding where animals occur in the water, which is often of management and conservation interest. In this study, we developed a hierarchical model that links counts of pinnipeds at terrestrial sites to sightings-at-sea and estimates abundance, spatial distribution, and the proportion of time spent on land (attendance probability). The structure of the model also allows for the inclusion of predictors that may explain variation in ecological and observation processes. We applied the model to Steller sea lions (Eumetopias jubatus) in Glacier Bay, Alaska using counts of sea lions from aerial photographic surveys and opportunistic in-water sightings from vessel surveys. Glacier Bay provided an ideal test and application of the model because data are available on attendance probability based on long-term monitoring. We found that occurrence in the water was positively related to proximity to terrestrial sites, as would be expected for a species that engages in central-place foraging. The proportion of sea lions in attendance at terrestrial sites and overall abundance estimates were consistent with reports from the literature and monitoring programs. The model we describe has benefit and utility for park managers who wish to better understand the overlap between pinnipeds and visitors, and the framework that we present has potential for application across a variety of study systems and taxa. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results